Channel Scan Architecture for Multiple Stimulus Multi-Touch Sensor Panels

ABSTRACT

A channel scan architecture for detecting touch events on a touch sensor panel is disclosed. The channel scan architecture can combine drive logic, sense channels and channel scan logic on a single monolithic chip. The channel scan logic can be configured to implement a sequence of scanning processes in a panel subsystem without intervention from a panel processor. The channel scan architecture can provide scan sequence control to enable the panel processor to control the sequence in which individual scans are implemented in the panel subsystem. Type of scans that can be implemented in the panel subsystem can include a spectral analysis scan, touch scan, phantom touch scan, ambient light level scan, proximity scan and temperature scan.

FIELD OF THE INVENTION

This relates to touch sensor panels that utilize multiple concurrentstimulation signals to detect and localize touch events, and moreparticularly, to a cost and power effective channel scan architecturecapable of implementing a sequence of scans without intervention from apanel processor.

BACKGROUND OF THE INVENTION

Many types of input devices are presently available for performingoperations in a computing system, such as buttons or keys, mice,trackballs, touch sensor panels, joysticks, touch screens and the like.Touch screens, in particular, are becoming increasingly popular becauseof their ease and versatility of operation as well as their decliningprice. Touch screens can include a touch sensor panel, which can be aclear panel with a touch-sensitive surface, and a display device thatcan be positioned behind the panel so that the touch-sensitive surfacecan substantially cover the viewable area of the display device. Touchscreens can allow a user to perform various functions by touching thetouch sensor panel using a finger, stylus or other object at a locationdictated by a user interface (UI) being displayed by the display device.In general, touch screens can recognize a touch event and the positionof the touch event on the touch sensor panel, and the computing systemcan then interpret the touch event in accordance with the displayappearing at the time of the touch event, and thereafter can perform oneor more actions based on the touch event.

Touch sensor panels can be formed from a matrix of drive and senselines, with sensors or pixels defined, in some embodiments, by where thedrive and sense lines cross over or come close to each other while beingseparated by a dielectric material. Drive or transmitting logic can becoupled to the drive lines, and sense or receiving channels can becoupled to the sense lines. During a scanning process, the drive logiccan drive each drive line with a stimulation signal, and the sensechannels can generate sense data indicative of the amount of chargeinjected into the sense lines due to the stimulation signal. A panelprocessor can identify touch locations based on the sense data, becausethe amount of charge is related to the amount of touch.

However, the voltage required by the drive logic for providing thestimulation signal can be much higher than the voltage required by thesense channels for sensing the injected charge. This can force the drivelogic and sense channels to be implemented in discrete chips, causingthe sensor panel circuitry to be larger in size and more expensive.

Further, involvement by the panel processor in the scanning process canoccupy a significant amount of time, increasing the processing burden ofthe panel processor beyond that which is necessary to identify anoccurrence or absence of a touch event based on sense data generatedfrom the scanning process. This significant amount of processing timecan make a processor too busy to perform other functions and can slowdown devices using a sensor panel. Additionally, processors typicallyconsume a significant amount of power during operation, which can beparticularly problematic when a sensor panel is used in conjunction witha hand held device, as many hand-held devices have a limited powersupply.

SUMMARY OF THE INVENTION

A channel scan architecture for detecting touch events on a touch sensorpanel is disclosed. The channel scan architecture can combine drivelogic, sense channels and channel scan logic on a single monolithicchip. The channel scan logic can be configured to implement a sequenceof scanning processes in a panel subsystem without intervention from apanel processor.

Providing sensor panel circuitry on a single chip achieves hardware costsavings over multiple chip circuitry. The use of multiple stimulationfrequencies and phases to sense touch events enables higher-power drivelogic to operate with a reduced voltage on the same chip as lower-powersense channels. Implementing touch scanning functionality in dedicatedlogic in the panel subsystem decreases the processing burden of thepanel processor.

The channel scan architecture can provide scan sequence control toenable the panel processor to control the sequence in which individualscans are implemented in the panel subsystem. Type of scans that can beimplemented in the panel subsystem can include, for example, a spectralanalysis scan, touch scan, phantom touch scan, ambient light level scan,proximity scan and temperature scan.

The spectral analysis scan can be used to select a clean frequency foruse in the scan of the touch sensors. The touch scan can be used toidentify an occurrence or absence of a touch event at the sensor panel.The phantom touch scan can be used to generate calibration data toadjust a baseline noise level associated with the touch sensors. Theambient light level scan can be used to identify an ambient light levelat the sensor panel. The proximity scan can be used to identify anoccurrence or absence of a proximity event at the sensor panel, such asan object hovering over the sensor panel. The temperature scan can beused to adjust parameters, such as channel gains, delays and the touchdata baseline for example, to compensate for temperature-related driftof such parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary computing system that can use multiplestimulation frequencies and phases to sense touch events with a channelscan architecture according to embodiments of the invention.

FIG. 2A illustrates an exemplary circuit for generating stimulationfrequencies for stimulating the drive lines on the touch sensor panelaccording to one embodiment of this invention.

FIG. 2B illustrates another exemplary circuit for generating stimulationfrequencies for stimulating the drive lines on the touch sensor panelaccording to one embodiment of this invention.

FIG. 2C illustrates another exemplary circuit for generating stimulationfrequencies for stimulating the drive lines on the touch sensor panelaccording to one embodiment of this invention.

FIG. 3A illustrates a simplified block diagram of N exemplary sensechannel or event detection and demodulation circuits according to oneembodiment of this invention.

FIG. 3B illustrates another simplified block diagram of N exemplarysense channel or event detection and demodulation circuits according toone embodiment of this invention.

FIG. 4 illustrates an exemplary channel scan architecture according toone embodiment of this invention.

FIG. 5 illustrates an exemplary flow diagram that can be performed bylogic associated with a panel subsystem according to one embodiment ofthis invention.

FIG. 6 illustrates an exemplary flow diagram that can be performed bylogic associated with a spectral analysis scan according to oneembodiment of this invention.

FIG. 7 illustrates an exemplary flow diagram that can be performed bylogic associated with a touch scan according to one embodiment of thisinvention.

FIG. 8 illustrates an exemplary flow diagram that can be performed bylogic associated with a phantom touch scan according to one embodimentof this invention.

FIG. 9 illustrates an exemplary flow diagram that can be performed bylogic associated with an ambient light level scan according to oneembodiment of this invention.

FIG. 10 illustrates an exemplary flow diagram that can be performed bylogic associated with a proximity scan according to one embodiment ofthis invention.

FIG. 11 illustrates an exemplary flow diagram that can be performed bylogic associated with a temperature scan according to one embodiment ofthis invention.

FIG. 12A illustrates an exemplary mobile telephone associated with achannel scan architecture according to one embodiment of this invention.

FIG. 12B illustrates an exemplary media player associated with a channelscan architecture according to one embodiment of this invention.

FIG. 12C illustrates an exemplary personal computer associated with achannel scan architecture according to one embodiment of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following description of preferred embodiments, reference is madeto the accompanying drawings where it is shown by way of illustrationspecific embodiments in which the invention can be practiced. It is tobe understood that other embodiments can be used and structural changescan be made without departing from the scope of the embodiments of thisinvention.

This relates to providing a cost and power effective architecture fordetecting touch events on a touch sensor panel. In particular, drivelogic, sense channels and channel scan logic can be provided on a singlemonolithic chip. Providing sensor panel circuitry on a single chipachieves hardware cost savings over multiple chip circuitry. The use ofmultiple stimulation frequencies and phases to sense touch eventsenables higher-power drive logic to operate with a reduced voltage onthe same chip as lower-power sense channels. Further, channel scan logiccan be provided to implement a sequence of scanning processes withoutintervention from a panel processor. Implementing touch scanningfunctionality in dedicated logic decreases the processing burden of thepanel processor.

Although some embodiments of this invention may be described herein interms of mutual capacitance touch sensors, it should be understood thatembodiments of this invention are not so limited, but are generallyapplicable to other types of touch sensors such as self capacitancetouch sensors. Furthermore, although the touch sensors in the touchsensor panel may be described herein in terms of an orthogonal array oftouch sensors having drive and sense lines arranged in rows and columns,it should be understood that embodiments of this invention are notlimited to row and columns or orthogonal arrays, but can be generallyapplicable to touch sensors arranged in any number of dimensions andorientations, including diagonal, concentric circle, andthree-dimensional and random orientations. In addition, the touch sensorpanel described herein can be either a single-touch or a multi-touchsensor panel, the latter of which is described in Applicant's co-pendingU.S. application Ser. No. 11/649,998 entitled “Proximity and Multi-TouchSensor Detection and Demodulation,” filed on Jan. 3, 2007, the contentsof which are incorporated by reference herein in their entirety for allpurposes. The touch sensor panel may have drive and sense lines formedon separate substrates, opposite sides of a single substrate, or on thesame side of a single substrate, some embodiments of the latter beingdescribed in U.S. patent application Ser. No. 12/110,075, entitled“Brick Layout and Stackup for a Touch Screen,” filed on Apr. 25, 2008,the contents of which are incorporated herein by reference in theirentirety for all purposes.

FIG. 1 illustrates exemplary computing system 100 that can use multiplestimulation frequencies and phases to sense touch events with a channelscan architecture according to embodiments of the invention. Computingsystem 100 can include one or more panel processors 102 and peripherals104, and panel subsystem 106. One or more panel processors 102 caninclude, for example, ARM968 processors or other processors with similarfunctionality and capabilities. However, in other embodiments, the panelprocessor functionality can be implemented instead by dedicated logic,such as a state machine. Peripherals 104 can include, but are notlimited to, random access memory (RAM) or other types of memory orstorage, watchdog timers and the like. Panel subsystem 106 can include,but is not limited to, one or more sense channels 108, channel scanlogic 110 and driver logic 114. Channel scan logic 110 can access RAM112, autonomously read data from the sense channels and provide controlfor the sense channels. In addition, channel scan logic 110 can controldriver logic 114 to generate stimulation signals 116 at variousfrequencies and phases that can be selectively applied to multiple rowsof touch sensor panel 124. In some embodiments, panel subsystem 106,panel processor 102 and peripherals 104 can be integrated into a singleapplication specific integrated circuit (ASIC).

Touch sensor panel 124 can include a capacitive sensing medium having aplurality of row traces or driving lines and a plurality of columntraces or sensing lines, although other sensing media can also be used.The drive and sense lines can be formed from a transparent conductivemedium such as Indium Tin Oxide (ITO) or Antimony Tin Oxide (ATO),although other transparent and non-transparent materials such as coppercan also be used. In some embodiments, the drive and sense lines can beperpendicular to each other, although in other embodiments othernon-Cartesian orientations are possible. For example, in a polarcoordinate system, the sensing lines can be concentric circles and thedriving lines can be radially extending lines (or vice versa). It shouldbe understood, therefore, that the terms “drive line” and “sense line,”“row” and “column,” “first dimension” and “second dimension,” or “firstaxis” and “second axis” as used herein are intended to encompass notonly orthogonal grids, but the intersecting traces or adjacent patternsof other geometric configurations having first and second dimensions(e.g. the concentric and radial lines of a polar-coordinatearrangement).

Where the drive and sense lines pass above and below (cross) each other(but do not make direct electrical contact with each other), or areadjacent to or nearby each other (in the case of drive and sense linesformed on the same side of a single substrate), the drive and senselines can essentially form pairs of electrodes. Each pair of electrodescan represent a capacitive sensing node and can be viewed as pictureelement (pixel) 126, which can be particularly useful when touch sensorpanel 124 is viewed as capturing an “image” of touch. (In other words,after processor 102 has determined whether a touch event has beendetected at each touch sensor in the touch sensor panel, the pattern oftouch sensors in the multi-touch panel at which a touch event occurredcan be viewed as an “image” of touch (e.g., a pattern of fingerstouching the panel). The capacitance between the pixel electrodesappears as a stray capacitance when the drive line for that pixel isheld at direct current (DC) voltage levels and as a mutual signalcapacitance Csig when the drive line is stimulated with an alternatingcurrent (AC) signal. The presence of a finger or other object near or onthe touch sensor panel can be detected by measuring changes to a signalcharge Qsig present at the pixels being touched, which is a function ofCsig. Each sense line of touch sensor panel 124 can drive sense channel108 (also referred to herein as an event detection and demodulationcircuit) in panel subsystem 106.

Computing system 100 can also include host processor 128 for receivingoutputs from panel processor 102 and performing actions based on theoutputs that can include, but are not limited to, moving an object suchas a cursor or pointer, scrolling or panning, adjusting controlsettings, opening a file or document, viewing a menu, making aselection, executing instructions, operating a peripheral deviceconnected to the host device, answering a telephone call, placing atelephone call, terminating a telephone call, changing the volume oraudio settings, storing information related to telephone communicationssuch as addresses, frequently dialed numbers, received calls, missedcalls, logging onto a computer or a computer network, permittingauthorized individuals access to restricted areas of the computer orcomputer network, loading a user profile associated with a user'spreferred arrangement of the computer desktop, permitting access to webcontent, launching a particular program, encrypting or decoding amessage, and/or the like. Host processor 128 can also perform additionalfunctions that may not be related to panel processing, and can becoupled to program storage 132 and display device 130 such as an LCDdisplay for providing a UI to a user of the device.

In some systems, sensor panel 124 can be driven by high-voltage driverlogic. The high voltages that can be required by the high-voltage driverlogic (e.g. 18V) can force the high-voltage driver logic to be formedseparate from panel subsystem 106, which can operate at much lowerdigital logic voltage levels (e.g. 1.7 to 3.3V). However, in embodimentsof the invention, on-chip driver logic 114 can replace the off-chip highvoltage driver logic. Although panel subsystem 106 can have low, digitallogic level supply voltages, analog or digital panel driver circuitrymay be implemented on chip. In one embodiment, panel driver circuitry114 can generate stimulus voltage levels up to twice the maximum voltageallowable for the process of the multi-touch ASIC (e.g. 1.7 to 3.3V) bycascoding two transistors. The high voltage supply can be furnished bycharge pump 115 that can also be integrated into the multi-touch ASIC.Although FIG. 1 shows charge pump 115 separate from driver logic 114,the charge pump can be part of the driver logic.

FIG. 2A illustrates one exemplary circuit 200 for generating stimulationfrequencies for stimulating drive lines on a touch sensor panelaccording to embodiments of the invention. In FIG. 2A, more than onenumerically controlled oscillator (NCO) 202 (e.g. NCOA, NCOB, NCOC),each generating a signed M-bit digital representation of a differentfrequency, can be summed in summing circuit 204, producing compositedigital waveform 206, which can be converted into an analog waveform byDAC 214. DAC 214 can generate two phases of the analog waveform, anon-inverted (0 degrees or positive phase) version 216 (referred to asVSTM_P), and an inverted (180 degrees or negative phase) version 218(referred to as VSTM_N) of the analog waveform. VSTM_N, VSTM_P, a commonmode voltage VSTM_CM 220 and 0V (see 222) are fed into switch matrix224. Following the switch matrix is an array of output buffers 226, oneper panel drive line. Control signal OBIN_SEL[ ] 228 allows independentselection of either VSTM_P, VSTM_N, VSTM_CM or 0V for each of the outputbuffers.

FIG. 2B illustrates another exemplary circuit 208 for generatingstimulation frequencies for stimulating drive lines on a touch sensorpanel according to embodiments of the invention. In FIG. 2B, more thanone NCO 202 are each fed into one or more DACs 210, producing separateanalog waveforms 212 VSTM_P_A 230, VSTM_N_A 232, VSTM_P_B 234, VSTM_N_B236, VSTM_P_C 238, and VSTM_N_C 240, which are fed into switch matrix224 along with common mode voltage VSTM_CM 220 and 0V 222. Followingswitch matrix 224 is an array of output buffers 226, one per panel driveline. Control signal OBIN_SEL[] 228 allows independent selection ofeither VSTM_P_A 230, VSTM_N_A 232, VSTM_P_B 234, VSTM_N_B 236, VSTM_P_C238, VSTM_N_C 240, VSTM_CM 220 or 0V (see 222) for each of the outputbuffers.

FIG. 2C illustrates exemplary circuit 208 according to an embodiment ofthe invention in which only one NCO 202 is fed into DAC 210, producingseparate analog waveforms 212 VSTM_P 230 and VSTM_N 232, which are fedinto switch matrix 224 along with common mode voltage VSTM_CM 220 and 0V222. In the embodiment illustrated in FIG. 2C, control signal OBIN_SEL[] 228 allows independent selection of either VSTM_P 230, VSTM_N 232,VSTM_CM 220 or 0V (see 222) for each of the output buffers. Note that ineither of FIGS. 2A, 2B or 2C, a composite waveform will be seen on thesense lines of the touch sensor panel.

FIG. 3A illustrates a simplified block diagram of N exemplary sensechannel or event detection and demodulation circuits 300 according to anembodiment of the invention. Each charge amplifier or programmable gainamplifier (PGA) 302 in sense channel 300 can be connected to analogfront end channel 309, which in turn can be connected to R signal mixers304. Beside PGA 302, analog front end channel 309 can includeanti-aliasing filter 301, ADC 303, and result register 305. Each signalmixer 304 multiplies the digital signal from analog front end channels309 with a demodulation signal generated by NCO 315 at the samestimulation frequencies generated by the circuits of FIGS. 2A and 2B.The demodulated output of each signal mixer 304 can be connected to aseparate accumulator 308 and results register 307. FIG. 3B illustrates asimplified block diagram of N exemplary sense channel or event detectionand demodulation circuits 300 according to an embodiment of theinvention in which only a single demodulator is used per channel.

A more detailed description of an exemplary touch sensor panel andassociated sense circuitry for using multiple stimulation frequenciesand phases to detect touch events is described in U.S. application Ser.No. 11/818,345 filed on Jun. 13, 2007 and entitled “MultipleSimultaneous Frequency Detection,” the contents of which areincorporated by reference herein in their entirety for all purposes.

A touch scan can be performed to capture multi-touch sense data withoutintervention from the panel processor, so that the sense data can beavailable for processing by the processor after a touch event hasoccurred. This can aid in the conservation of power as it does notrequire intervention from the panel processor during the scan. In thetouch scan, composite multi-touch data can be captured over multipletiming sequences (e.g, 16 sequences, 200 us each) and posted into abuffer. Since this multi-touch data is composite data, a separate matrixdecode logic can be utilized to extract the actual per-pixel Csig valuesand post them to memory, such as SRAM, where the processor can accessthe data for further processing after a touch event has occurred. Eachtouch scan can include several individual image scans, each performed atone or multiple different stimulus frequencies. The touch scan canprecede or follow a scan in an auto-scan mode or can be performed in aseparate scan.

A more detailed description of an auto-scan mode is described in U.S.application Ser. No. 12/022,572 filed on Jan. 30, 2008 and entitled“Auto Scanning for Multiple Frequency Stimulation Multi-Touch SensorPanels,” the contents of which are incorporated by reference herein intheir entirety for all purposes.

FIG. 4 illustrates exemplary channel scan architecture 400 according toone embodiment of this invention. In this architecture, processor 102provides control to panel scan logic 408 to implement a sequence ofscanning processes using components of subsystem 106, including sensechannels 414, drive channels 426, and auxiliary channels anddemodulators 410. Auxiliary channels and demodulators 410 pertain tosensing circuitry associated with sensors other than touch sensors, suchas, for example, light, proximity and temperature sensors. Configurationregisters 428 can store configuration data (counter values, phaseincrements, etc.) utilized by panel scan logic 408 in controlling eachcomponent of subsystem 106. Stimulation matrix 418 can determine thestimulation signals to be provided by drive channels 426, and matrixdecode logic 420, result RAM 422 and matrix decode RAM 424 can be usedto extract the per-pixel Csig values on the sense side. Panel scan logic408 can be clocked by high frequency oscillator (HFO) 406 or lowfrequency oscillator (LFO) 402. HFO 406 and LFO 402 can be managed byclock and power manager 404, which can enable or disable the oscillatorsdepending on whether a scan occurs in an active mode or auto-scan modefor example.

FIG. 5 illustrates an exemplary flow diagram that can be performed bydedicated logic associated with panel subsystem 106 according to oneembodiment of this invention. Each of the described scans can beimplemented by panel scan logic 408 of FIG. 4 in a particular sequencewithout intervention from panel processor 102. For example, during aparticular scan sequence, subsystem 106 can perform a spectral analysisscan (step 500) followed by a touch scan (505). Depending on whetherthey are enabled (steps 510, 520, 530, 540), subsystem 106 can perform aphantom scan (step 515), ambient light level scan (step 525), proximityscan (535) and a temperature scan (step 545). FIGS. 6-11 describeparticular operations that can be associated with each scan in an activemode, in which processor 102 is active to receive an interrupt fromsubsystem 106 after each scan is implemented.

FIG. 6 illustrates an exemplary flow diagram that can be performed bylogic associated with the spectral analysis scan according to oneembodiment of this invention. The spectral analysis scan can be used toselect a clean frequency for use in the scan of the touch sensors. Inparticular, subsystem 106 can configure the system for the spectralanalysis scan (step 600), which can entail adjusting gains and delays ofthe appropriate circuitry. With the touch sensor drive channels disabled(e.g., driver logic 114 in FIG. 1 disabled so that no stimulationsignals are sent to any of the drive lines in touch sensor panel 124),subsystem 106 can perform in-phase and quadrature demodulation, fordifferent frequencies, of the sum of all analog output data at the touchsensor sense channels (step 610) for a number of sample clocks (e.g.,mixers 304 and NCOs 315 in each sense channel 300 in FIG. 3 can performin-phase and quadrature demodulation at different frequencies). Whencomplete, the demodulated data can be posted to result registers (620)(e.g., result RAM 422 in FIG. 4), and an interrupt can be generated tothe panel processor (630) notifying the processor that the spectralanalysis scan is complete. At this stage, the processor can process theresult data to select a clean frequency for use in the subsequent touchscan operation. A more detailed description of a spectral analysis scanis described in U.S. application Ser. No. 11/818,454 entitled “Detectionof Low Noise Frequencies for Multiple Frequency Sensor PanelStimulation,” filed on Jun. 13, 2007, the contents of which areincorporated by reference herein in their entirety for all purposes.

FIG. 7 illustrates an exemplary flow diagram that can be performed bylogic associated with the touch scan according to one embodiment of thisinvention. The touch scan can be used to identify an occurrence orabsence of a touch event at the sensor panel. In particular, subsystem106 can configure the system for the touch scan (step 700), which canentail adjusting gains and delays of the appropriate circuitry. With thetouch sensor drive channels enabled (e.g., driver logic enabled so thatstimulation signals are sent to the drive lines in touch sensor panel asspecified by the stimulation matrix RAM 418 of FIG. 4), subsystem 106can concurrently stimulate the touch sensors with different stimulationsignals (step 710) for a number of sample clocks. When complete, thedemodulated data can be posted to result registers (720). Since thedemodulated data represents composite sense data, subsystem 106 candecode the composite touch data into sensor-specific touch data (i.e.,the per-pixel Csig values) using the matrix decode finite state machine420 in FIG. 4, and post the decoded data into the result registers (step740). Steps 710-740 can be repeated for multiple timing sequences usingthe stimulation signals identified in the stimulation matrix. Whencomplete, an interrupt can be generated to the panel processor (750)notifying the processor that the touch scan is complete.

FIG. 8 illustrates an exemplary flow diagram that can be performed bylogic associated with the phantom touch scan according to one embodimentof this invention. The phantom touch scan can be used to generatecalibration data to adjust a baseline noise level associated with thetouch sensors. In particular, subsystem 106 can configure the system forthe phantom touch scan (step 800), which can entail adjusting gains anddelays of the appropriate circuitry. With the touch sensor drivechannels disabled, subsystem 106 can perform a touch scan demodulationat the touch sensor sense channels (step 810) for a number of sampleclocks at a particular frequency (e.g., a mixer 304 and NCO 315 in eachsense channel 300 in FIG. 3 can demodulate the no-stimulation senseoutputs of the touch sensor panel). When complete, the demodulated datacan be posted to result registers (820), and an interrupt can begenerated to the panel processor (830) notifying the processor that thephantom touch scan is complete. A more detailed description of phantomscanning and calibration is described in U.S. application Ser. No.11/650,204 entitled “Error Compensation for Multi-Touch Surfaces,” filedon Jan. 3, 2007, the contents of which are incorporated herein byreference in their entirety for all purposes.

FIG. 9 illustrates an exemplary flow diagram that can be performed bylogic associated with an ambient light level scan according to oneembodiment of this invention. The ambient light level scan can utilizeone or more ambient light sensors incorporated into the sensor panel,and can be used to identify an ambient light level at the sensor panel.In particular, subsystem 106 (or alternatively, host processor 128 inFIG. 1), can configure the system for the ambient light level scan (step900), which can entail adjusting gains and delays of the appropriatecircuitry. Subsystem 106 (or the host processor) can capture lightsensor data at light sensor sense channels (step 910) for a number ofsample clocks (e.g., an auxiliary sense channel 410 in FIG. 4 can detectthe ambient light level from a signal received from an ambient lightsensor). When complete, the captured data can be posted to resultregisters (920), and an interrupt can be generated to the panelprocessor (930) notifying the processor that the ambient light levelscan is complete. Alternatively, the ambient light sensor can generatedigital values that can be communicated over a digital interface to thehost processor, where similar processing can be performed. A moredetailed description of a sensor panel including an ambient light sensoris described in U.S. application Ser. No. 11/800,293 entitled“Luminescence Shock Avoidance in Display Devices,” filed on May 4, 2007,the contents of which are incorporated by reference herein in theirentirety for all purposes.

FIG. 10 illustrates an exemplary flow diagram that can be performed bylogic associated with a proximity scan according to one embodiment ofthis invention. The proximity scan can be used to identify an occurrenceor absence of a proximity event at the sensor panel, such as an objecthovering over the sensor panel. In particular, subsystem 106 canconfigure the system for the proximity scan (step 1000), which canentail adjusting gains and delays of the appropriate circuitry. With theproximity sensor drive channels enabled, subsystem 106 can stimulate theproximity sensors (step 1010) for a number of sample clocks. Whencomplete, the demodulated data can be posted to result registers (1020),and an interrupt can be generated to the panel processor (1030)notifying the processor that the proximity scan is complete. A moredetailed description of proximity sensors is described in U.S.application Ser. No. 11/818,345 entitled “Proximity and Multi-TouchSensor Detection and Demodulation,” previously incorporated by referenceabove.

FIG. 11 illustrates an exemplary flow diagram that can be performed bylogic associated with a temperature scan according to one embodiment ofthis invention. The temperature scan can utilize a temperature sensorincorporated into computing system 100, such as in panel subsystem 106for example. The temperature scan can be used to adjust parameters, suchas channel gains, delays and the touch data baseline for example, tocompensate for temperature-related drift of such parameters. Inparticular, subsystem 106 can configure the system for the temperaturescan (step 1100), which can entail adjusting gains and delays of theappropriate circuitry. Subsystem 106 can capture temperature data fromthe temperature sensor (step 1110) for a number of sample clocks. Whencomplete, the captured data can be posted to result registers (1120),and an interrupt can be generated to the panel processor (1130)notifying the processor that the temperature scan is complete.

In another embodiment, the scanning operations described in FIGS. 7-11can be implemented in an auto-scan mode in which processor 102 isinactive. In this embodiment, since processor 102 is in an inactivestate, panel subsystem 10 can wait until after all of the scans in aparticular scan sequence have completed before awakening processor 102,rather than generating an interrupt to processor 102 after each scan asdescribed above.

Panel scan logic 408 can include a scan sequence control (e.g., as shownby “PSCN_CTRL” and “PSCN_CFG” in FIG. 4). The scan sequence control canenable processor 102 to control the sequence in which the individualscans are performed by panel subsystem 106. For example, in certainapplications, it may be beneficial to perform the temperature scan priorto the touch scan to calibrate out any temperature-related effects priorto touch scanning. Similarly, it may be beneficial to perform theproximity scan prior to the touch scan in certain applications, such aspower sensitive applications for example. For instance, it may bebeneficial to only perform the touch scan when an object is within acertain proximity of the touch panel. In one embodiment, the proximityscan can be used to detect if an object (such as a finger for example)is close by, and if the object is within a certain distance to thepanel, then the touch scan is performed; otherwise the touch scan can beskipped.

According to an embodiment of the invention, the scan sequence controlcan be implemented as a scan sequence memory (e.g., in configurationregisters 428), with each memory location (1 to N) indicating the orderof scanning. For example, the memory can be 5 memory locations deep,with each memory location containing a 3 bit value that indicates thetype of scan, as illustrated by the following:

-   -   0=Touch scan    -   1=Phantom touch scan    -   2=Ambient light level scan    -   3=Proximity scan    -   4=Temperature scan

In this example, it can be presumed that the spectral analysis scan willalways be implemented first in a scan sequence. According to the aboveexample, the following exemplary scan sequence memory configuration:

Memory Location Data 0 1 1 2 2 3 3 4 4 0can represent the following scan sequence after completion of thespectral analysis scan: phantom touch scan→ambient light levelscan→proximity scan→temperature scan→touch scan. Processor 102 can setthe scan sequence in configuration registers 428, allowing panel scanlogic 408 to implement the scan sequence based on the set data withoutintervention from processor 102.

FIG. 12A illustrates exemplary mobile telephone 1236 that can includetouch sensor panel 1224 and display device 1230, the touch sensor panelassociated with a channel scan architecture according to embodiments ofthe invention.

FIG. 12B illustrates exemplary digital media player 1240 that caninclude touch sensor panel 1224 and display device 1230, the touchsensor panel associated with a channel scan architecture according toembodiments of the invention.

FIG. 12C illustrates exemplary personal computer 1244 that can includetouch sensor panel 1224 and display 1230, the touch sensor panel and/ordisplay of the personal computer (in embodiments where the display ispart of a touch screen) associated with a channel scan architectureaccording to embodiments of the invention. The mobile telephone, mediaplayer and personal computer of FIGS. 12A, 12B and 12C can achieveimproved touch panel operation by utilizing a channel scan architectureaccording to embodiments of the invention.

Although embodiments of this invention have been fully described withreference to the accompanying drawings, it is to be noted that variouschanges and modifications will become apparent to those skilled in theart. Such changes and modifications are to be understood as beingincluded within the scope of embodiments of this invention as defined bythe appended claims.

1. A computing device comprising: a sensor panel including a pluralityof touch sensors; and a single integrated circuit including drive logicconfigured to stimulate the sensor panel, sense channels configured tosense touch applied to the sensor panel, panel subsystem logicconfigured to perform a scan of the touch sensors to generate touchsense data, and a processor configured to process the touch sense datato identify an occurrence or absence of a touch event at the sensorpanel.
 2. The computing device of claim 1, wherein the scan of the touchsensors includes concurrently stimulating the touch sensors withmultiple stimulation frequencies and phases.
 3. The computing device ofclaim 1, wherein the processor is configured to process frequencyselection data to select a clean frequency for use in the scan of thetouch sensors, and the panel subsystem logic is configured to perform aspectral analysis scan of the touch sensors to generate the frequencyselection data without intervention from the processor.
 4. The computingdevice of claim 3, wherein the spectral analysis scan includesperforming quadrature demodulation of different frequencies at sensechannels associated with the touch sensors.
 5. The computing device ofclaim 1, wherein the processor is configured to process calibration datato adjust a baseline noise level associated with the touch sensors, andthe panel subsystem logic is configured to perform a no stimulation scanof the touch sensors to generate the calibration data withoutintervention from the processor.
 6. The computing device of claim 1,wherein the sensor panel includes a plurality of light sensors, theprocessor is configured to process light sense data to identify anambient light level at the sensor panel, and the panel subsystem logicis configured to perform an ambient light level scan of the lightsensors to generate the light sense data without intervention from theprocessor.
 7. The computing device of claim 1, wherein the sensor panelincludes a plurality of proximity sensors, the processor is configuredto process proximity sense data to identify an occurrence or absence ofa proximity event at the sensor panel, and the panel subsystem logic isconfigured to perform a scan of the proximity sensors to generate theproximity sense data without intervention from the processor.
 8. Thecomputing device of claim 1, wherein the computing device includes atemperature sensor, the processor is configured to process temperaturedata to calibrate parameters associated with the touch sensors that aresusceptible to temperature-related drift, and the panel subsystem logicis configured to perform a scan of the temperature sensor to generatethe temperature data without intervention from the processor.
 9. Thecomputing device of claim 1, wherein the panel subsystem logic performseach of a plurality of different types of scans, without interventionfrom the processor, in a sequence controlled by the processor.
 10. Anapplication-specific integrated circuit comprising: a plurality of firstdrive channels configured to stimulate a touch sensor panel; a pluralityof first sense channels configured to sense a touch event at the touchsensor panel; and panel subsystem logic configured to control theplurality of first drive channels and the plurality of first sensechannels during a scan of the touch sensor panel.
 11. Theapplication-specific integrated circuit of claim 10, wherein the scan ofthe touch sensor panel includes concurrently stimulating the touchsensors with multiple stimulation frequencies and phases.
 12. Theapplication-specific integrated circuit of claim 10, wherein the panelsubsystem logic is configured to perform a spectral analysis scan of thetouch sensor panel to generate frequency selection data.
 13. Theapplication-specific integrated circuit of claim 10, further comprising:a plurality of second drive channels configured to stimulate a proximitysensor panel; a plurality of second sense channels configured to sense aproximity event at the proximity sensor panel; and panel subsystem logicconfigured to control the plurality of second drive channels and theplurality of second sense channels during a scan of the proximity sensorpanel.
 14. The application-specific integrated circuit of claim 10, theapplication-specific integrated circuit being incorporated within acomputing device.
 15. A computing device comprising: a sensor panelincluding a plurality of touch sensors; and a panel subsystem includinga sense channel and decode logic, the sense channel coupled to theplurality of touch sensors, the sense channel superposing output signalsgenerated by the plurality of touch sensors and generating compositesense data based on the superposed output signals, and the decode logicconfigured to decode the composite sense data into sensor-specific sensedata.
 16. The computing device of claim 15, wherein the panel subsystemfurther comprises spectral scan logic, the spectral scan logicconfigured to perform a spectral analysis scan of the sensor panel. 17.A method for detecting and processing touch events on a touch sensorpanel, comprising: combining drive logic and sense channels on a singlemonolithic chip configured for being coupled to the touch sensor panel;and controlling the drive logic and sense channels during a touchscanning process from within the chip without intervention from anon-chip processor.
 18. The method of claim 17, further comprisingperforming a spectral analysis scan of the touch sensor panel fromwithin the chip without intervention from the on-chip processor.
 19. Themethod of claim 17, further comprising performing a phantom touch scanof the touch sensor panel from within the chip without intervention fromthe on-chip processor.
 20. A mobile telephone comprising: a sensor panelincluding a plurality of touch sensors; and a single integrated circuitincluding drive logic configured to stimulate the sensor panel, sensechannels configured to sense touch applied to the sensor panel, panelsubsystem logic configured to perform a scan of the touch sensors togenerate touch sense data, and a processor configured to process thetouch sense data to identify an occurrence or absence of a touch eventat the sensor panel.
 21. A portable media player comprising: a sensorpanel including a plurality of touch sensors; and a single integratedcircuit including drive logic configured to stimulate the sensor panel,sense channels configured to sense touch applied to the sensor panel,panel subsystem logic configured to perform a scan of the touch sensorsto generate touch sense data, and a processor configured to process thetouch sense data to identify an occurrence or absence of a touch eventat the sensor panel.
 22. A personal computer comprising: a sensor panelincluding a plurality of touch sensors; and a single integrated circuitincluding drive logic configured to stimulate the sensor panel, sensechannels configured to sense touch applied to the sensor panel, panelsubsystem logic configured to perform a scan of the touch sensors togenerate touch sense data, and a processor configured to process thetouch sense data to identify an occurrence or absence of a touch eventat the sensor panel.